The present application relates to an apparatus for monitoring the movement of paper in a printing apparatus. It particularly relates to use with a printer for printing upon a continuous paper web.
A continuous paper web is generally provided in printing in the form of a roll of paper. Printers upon paper rolls is used in many applications. In financial machines such as autotellers and check sorting machines a concealed printer is generally provided to keep a visible record of transactions made or recorded. Concealed printers are also to be found in cash registers, electronic analyzing equipment, compact electronic graph plotters, chart recorders and the like. The present invention is particularly directed towards detecting paper movement problems in concealed printers where opertor oversight is not available.
The general function of any printing machine is to cause a printing device to produce a line of printing. Thereafter the paper web is advanced by the distance of one or more line spacings and the printing head once again executes a line of printing. In the past monitors have relied upon electrical signalling between the printer and the monitor itself in order to indicate when the paper should be executing a line advance. The present invention seeks to improve over this situation by providing that the monitor is reliant for its function only upon paper movement and not in any subservient way upon the actions of the printer. The present invention thereby seeks to achieve a true add-on capability for such a monitor irrespective of the type of printer employed.